Which component is found on a PSC motor that is typically absent on an ECM motor?

The correct choice is the capacitor. In a Permanent Split Capacitor (PSC) motor, a capacitor is used to create a phase shift for the motor windings, which helps in starting the motor and improving its efficiency. PSC motors rely on this capacitor for proper operation, as it enhances the starting torque and contributes to smoother running.

In contrast, Electronically Commutated Motors (ECMs) are designed with built-in electronic controls that allow for precise speed and torque regulation without the need for an external capacitor. The design of ECMs includes features that allow them to operate efficiently across a range of speeds, which eliminates the necessity of a capacitor for starting and running. Thus, the absence of a capacitor is a distinct difference between PSC motors and ECMs.

This understanding of motor components and their functions is fundamental for HVAC technicians, as it aids in diagnosing motor-related issues and in selecting the appropriate motor type for specific applications. Understanding the differences in motor designs leads to better maintenance practices and equipment performance.